Step 2: Build the Legs
Once the cores were glued in, I planed the legs to final thickness. Be careful how you sneak up on the final dimension as you need to take the same amount off of each side of the leg to keep the corner joints centered. Once at the final thickness, I beveled the edges and then trimmed the legs to final length.
To cut the mortises, I built a custom sled for my plunge router. It's a simple design - just a lexan sheet with adjustable hardwood cleats. The cleats can be adjusted in or out to allow the router to follow the workpiece - you can even cut off-center slots if required. A good tip for making sure your bit is centered, is to take a scrap that is the same width as your workpiece, center the bit as best you can, make a shallow cut, then rotate the sled around 180 degrees on the piece and see if your bit is still centered in the slot.
I had something like 54 mortises to cut, so I came up with a very simple "jig" that consisted of a few blocks of wood screwed to my work bench (see images). Two blocks located the leg position, and then two stop-blocks were clamped in place to control the length of the cut. Working this way, it didn't take much time to precisely cut all 54 mortises.